The present disclosure generally relates to a low-speed bus message protocol, and more particularly relates to methods and circuitry for low-speed bus time stamping and triggering.
Inter-Integrated Circuit (I2C) interface is typically used for attaching lower-speed peripheral Integrated Circuits (ICs) to higher-speed processors and microcontrollers. Lower-speed peripheral ICs are commonly referred to as slave devices, whereas a higher-speed processor or microcontroller is commonly referred to as a master device. Often, a slave device can be coupled to a peripheral device such as a sensor, a gyroscope, a compass, a microphone, and the like. The slave device can be configured to monitor and/or control operations of the peripheral device coupled to the slave device.
In I2C message protocol, a simultaneous operation by two or more slave devices can utilize a common trigger signal (e.g., generated by a master device), which is independent of an I2C low-speed serial bus. Similarly, in order to determine when an event occurred (e.g., measurement performed by a peripheral device coupled to a slave device), each slave device uses a dedicated line feeding back to the master device for signaling to the master device a time when the event occurs. For each slave device, the master device can capture a state of a real time clock (i.e., time of event, or timestamp of event) when the master device receives an event marker signal from the slave device. The disadvantage of this approach is a number of additional communication lines (i.e., board traces) between the master device and the slave devices, and additional signal pins that are required.